This research is an inquiry into the experience-based modification of infant perception. Its overall objective is to provide a fine-grained analysis of the effects of early visual stimulation on the development of the infant's discriminative competence. The experimental design involves (1) the exposure of different groups of 3- to 4-month-old infants to two contrasting visual stimuli under a variety of specific perceptual training conditions and (2) the subsequent assessment of their capacity to detect these same stimuli in new contexts. The training conditions, which essentially seek to teach the infant that the exposed stimuli signal forthcoming events, vary in terms of (a) whether the stimuli are functionally discriminative or not (i.e., whether they signal different or identical consequences) and (b) whether the infant is active or passive in the situation (i.e., whether he is required to make instrumental responses or not). The findings should advance our understanding of the mechanisms which govern perceptual development in early life.